The present invention relates to a screening apparatus for efficiently separating coarse material from finer material.
More specifically, the present invention relates to a screening apparatus for separating certain types of material such as earth, sand, bits of gravel, etc. With several screening apparatus known in the art, the material is trapped onto a vibrating screen. The screen has meshes having a specific size according to the screening that is desired. Normally, the material is screened two or three times to maximize the quality of the end product. Also, In many cases, a hopper is provided at the entry of the screening apparatus.
There is a great demand for earth material. As the cost of transport is increasing, the merchant tries to treat the earth material on the spot. Then, the ground is excavated, and the earth is led down directly onto the vibrating screen. In many cases, the material that is screened has to be classified. In certain cases, during the screening operation, components are added to the screened material.
It has to be noted that most of the screening apparatus are very big and are mounted on wheels or on trucks with hoppers. It is difficult to move these screening apparatus. Also, these big screening apparatus have sometimes problems when they are loaded with material containing stump, wood or big rocks that can block the operation of the screening apparatus.
Known in the art, there is the U.S. Pat. No. 5,082,555, granted on Jan. 21, 1992. This patent describes a soil feeder apparatus for use above an angled screen soil separating apparatus and adapted to feed soil material to be separated over a time period onto the angled screen of the soil separating apparatus. The apparatus comprises a hopper body having walls defining a space within the hopper body to receive soil material; means to tilt the hopper body about an axis; timing means to activate the means to tilt for a defined time period and to return rapidly the hopper body to a generally horizontal position; and a bracket means to mount the hopper body on the separating apparatus. When operating this apparatus, it has been found that it operates correctly only when the soil material to be separated is very dry. When the soil material is wet, it sticks on the bottom surface of the hopper body to a point where the apparatus does not operate efficiently at all.
Known in the art, there is also the U.S. Pat. No. 4,256,572 granted on Mar. 17, 1991. This patent describes a portable screening apparatus for separating coarse material from finer material. It comprises a material separating shaker screen sloping downward from near the upper edge of the tall end of the frame to near the upper edge of the short end of the frame; an outfeed conveyor extending from within the frame through one of the sides to carry finer material out of the frame; and means for directing finer material which falls through the shaker screen to the conveyor. One drawback with the above-mentioned apparatus is that there is no means for regulating the feeding of material to be screened onto the shaker screen.
Also known in the art, there are the U.S. Pat. No. 4,956,078 granted on Sep. 11, 1990; U.S. Pat. No. 4,609,405 granted on Sep. 2, 1986; U.S. Pat. No. 4,190,526 granted on Feb. 26, 1980; and U.S. Pat. No. 3,729,087 granted on Apr. 24, 1973 which relate to different kinds of hopper or diffuser for granular material. None of the above patents provide an efficient and simple solution for regulating the feeding of the material to be screened onto the material separating shaker screen of the apparatus shown in the U.S. Pat. No. 4,265,572.
Also known in the art, there are the U.S. Pat. No. 4,493,767 granted on Jan. 15, 1985; U.S. Pat. No. 4,177,900 granted on Dec. 11, 1979; U.S. Pat. No. 3,372,806 granted on Mar. 12, 1968; U.S. Pat. No. 2,836,298 granted on May 27, 1958; and U.S. Pat. No. 2,640,592 granted on Jun. 2, 1953 which relate to different kinds of conveyors. None of the above-mentioned patents provide an efficient and simple solution for regulating the feeding of the material to be screened onto the shaker screen of the apparatus shown in the U.S. Pat. No. 4,256,572.
An object of the present invention is to provide a screening apparatus that is provided with means for regulating the feeding of the material to be screened onto its shaker screen so that an efficient screening can be performed even when the material contains big unwanted objects such as stomp or big rocks, or even if the material is wet.